Form 1040-NR: The Short Guide for Non-Resident Founders

You incorporated a U.S. company from your kitchen table in Berlin, Bangalore, or São Paulo. You’ve never set foot in Delaware. So why is the IRS asking about a personal tax return?

If you’re a founder who lives outside the United States but earns money through a U.S. business, Form 1040-NR, the U.S. Nonresident Alien Income Tax Return, is the form that may put you on the IRS’s radar. It’s widely misunderstood: some founders file it when they don’t need to, and others ignore it until a penalty notice arrives. This guide explains what Form 1040-NR is, whether you actually have to file it as a non-resident founder, how your U.S. income gets taxed, and the 2026 deadlines that apply to you.

TL;DR

• Form 1040-NR is the U.S. income tax return for nonresident aliens, the non-resident version of Form 1040.
• Owning a U.S. company does not automatically require it. You file based on the income you personally receive.
• You generally file if you have income effectively connected to a U.S. trade or business, or U.S.-source income that was not fully taxed at the source.
• ECI is taxed at graduated rates on net profit. Passive FDAP income is taxed at a flat 30%, or a lower treaty rate.
• For the 2025 tax year, the deadline is April 15, 2026 (if you had U.S. wage withholding) or June 15, 2026 (the typical founder case).

What Is Form 1040-NR?

Form 1040-NR is the federal income tax return for nonresident aliens, the IRS term for individuals who are neither U.S. citizens nor U.S. tax residents. It is the non-resident counterpart to the standard Form 1040 that citizens and residents file.

You use it to report U.S.-source income, claim any tax treaty benefits you’re entitled to, calculate what you owe, and settle up with the IRS for income that wasn’t already taxed at the source.

A few features make it different from the resident Form 1040: nonresident filers generally cannot take the standard deduction, cannot file a joint return with a spouse, and can claim only a limited set of credits. That's why getting the details right, especially treaty positions and deductions, matters.

First Question: Are You Actually a Non-Resident for U.S. Tax Purposes?

Before worrying about the form, confirm your status. The IRS treats you as a U.S. tax resident if you meet either of two tests:

• The green card test. You’re a lawful permanent resident at any point in the year.
• The substantial presence test. You were physically present in the U.S. for at least 31 days this year and 183 days over a weighted three-year period (all of this year’s days, one-third of last year’s, and one-sixth of the year before).

If you meet neither test, you’re a nonresident alien, and Form 1040-NR is your form. Most founders who run a U.S. company remotely, visiting only occasionally, fall comfortably on the nonresident side. But keep a record of your travel days: a few long trips can quietly push you over the 183-day line.

Do You Actually Need to File Form 1040-NR?

This is where most founders get tripped up. The trigger isn’t “I own a U.S. company.” The trigger is the type of income you personally receive and whether it was already taxed. You generally must file if you are a nonresident who:

• Was engaged in a trade or business in the United States during the year (even with no income, in many cases); or
• Had U.S.-source income on which not enough tax was withheld at the source; or
• Owes special U.S. taxes (for example, certain taxes on a U.S. tax-favored account); or
• Is filing on behalf of a deceased person, estate, or trust that would have had to file.

To apply these rules, you need to understand two categories of income that drive almost everything on Form 1040-NR: ECI and FDAP.

How a Non-Resident’s U.S. Income Is Taxed

Effectively Connected Income (ECI)

ECI is income connected to running an active U.S. trade or business, the kind a hands-on founder typically generates. It’s reported on page 1 of Form 1040-NR and taxed at the same graduated rates that apply to U.S. citizens and residents, after allowable business deductions. You’re taxed on net profit, not gross receipts.

Fixed, Determinable, Annual, or Periodical Income (FDAP)

FDAP is passive U.S.-source income such as dividends, interest, and royalties. It’s reported on Schedule NEC and taxed at a flat 30% rate (or lower if a tax treaty reduces it), with no deductions allowed. FDAP is usually taxed through withholding at the source. If the payer withheld the correct amount, you often don’t need to file for that income.

Why this distinction matters: ECI is taxed on profit at graduated rates. FDAP is taxed on the gross amount at a flat 30% (or treaty) rate. Misclassifying one as the other can mean overpaying or underpaying and triggering penalties.

How This Plays Out by Entity Type

The biggest source of confusion is the gap between what your company files and what you file personally. They are separate obligations.

The takeaway: a foreign-owned single-member LLC with no U.S. trade or business often has no personal 1040-NR obligation, but it almost always still owes the Form 5472 entity filing, which carries a steep penalty (currently $25,000) for being late or missing.

Effectively connected, or not? It's a judgment call. Whether your business is “engaged in a U.S. trade or business” depends on facts like where the work is performed, whether you have U.S. employees or an office, and how regular the activity is. Two founders with identical LLCs can land on opposite sides of this line.

What You Need Before You File

• A U.S. taxpayer ID. You’ll need an ITIN if you’re not eligible for an SSN. Apply with Form W-7, which can be submitted alongside your return.
• Records of your U.S.-source income and any tax already withheld (for example, Forms 1042-S or K-1s).
• Your treaty position, if any. Check whether your country has a tax treaty with the U.S. that reduces rates on your type of income.
• Supporting documents for deductions tied to your effectively connected (ECI) business income.

2026 Deadlines You Can't Miss

For the 2025 tax year, two due dates apply:

Need more time? File Form 4868 by your regular due date for an automatic extension to file. An extension to file is not an extension to pay. Tax owed is still due by the original deadline, and interest accrues on late payments.

Don’t Leave Treaty Benefits on the Table

The U.S. has income tax treaties with dozens of countries. Depending on where you’re a tax resident, a treaty may cut the 30% FDAP rate on dividends, interest, or royalties, sometimes to 15%, 10%, or even zero. You claim it by disclosing your position on the return (and on Schedule OI). Skipping this means defaulting to the full statutory rate and overpaying.

Common Mistakes Non-Resident Founders Make

• Assuming the entity return covers them personally. Forms 5472, 1065, or 1120 are the company’s filings, not your personal 1040-NR.
• Filing a 1040-NR when none is required, creating paperwork that didn’t exist.
• Misclassifying ECI as FDAP (or vice versa), leading to the wrong rate and deductions.
• Missing the Form 5472 deadline on a foreign-owned single-member LLC, a $25,000 penalty trap.
• Ignoring treaty benefits and overpaying on passive income.
• Tracking U.S. days carelessly and accidentally becoming a U.S. tax resident.

Where to Get Form 1040-NR

Download Form 1040-NR and its schedules from the IRS directly: the Form 1040-NR PDF and the official instructions sit on the "About Form 1040-NR" page, alongside Schedule NEC (for FDAP income) and Schedule OI (for treaty positions).

You can file on paper or, in many cases, e-file through tax software that supports nonresident returns. If you also need an ITIN, attach Form W-7 to the return.

How Skala Can Help

Skala handles the company side that sits under your personal return: U.S. formation with an EIN, a registered agent, a U.S. mailing address, and annual compliance filings like the Delaware franchise tax. For the 1040-NR itself and your treaty position, you'll want a cross-border tax advisor — and Skala can help you find a vetted tax advisor or attorney. Skala itself keeps the company compliant, not your personal return.

Free, lawyer-drafted legal templates — NDAs, contractor and employment agreements, SAFEs, and more — are also on the platform.